The delicate white ornaments, made with off-white oven-bake clay and a piercing tool, were insipred by pierced creamware, such as the covered pot and bowl, first popularized by Leeds Pottery, in England, in the 18th century.
Rolling Oven-Bake Clay
Working on a nonstick baking mat, place oven-bake clay between 2 thin wooden slabs; use these as runners for the rolling pin. Roll out the clay, keeping the edges of the pin on the slabs, until it is of uniform thickness, about 3/16 inch.
From off-white clay, cut out an ornament using a scalloped biscuit cutter (if you can't find an oval, buy a round cutter and shape it). Starting at either the edge or the center of the ornament, use brass tubes (available at crafts and hardware stores) to pierce designs into the clay. For diamonds, squeeze the end of a square piece of tubing with needlenose pliers; for ovals, use the same technique on a round tube. Bake ornament, following manufacturer's instructions. Once cooled, use white craft glue to attach a loop of ribbon to the back.